1. Field of the Invention
This invention generally relates to a non-contact position detection device, and in particular, relates to a device which detects a position by detecting a magnetic field generated from a magnet with an electromagnetic conversion element. In addition, this invention generally relates to a pointing device which is connected to an information processing apparatus such as a personal computer, a PDA, a cellular phone, a navigation system or the like to be used when position information or direction information are input, and in particular, relates to a pointing device which is capable of determining or settling an input. Further, this invention relates to an input device used to input an instruction into a personal computer or the like, and in particular, relates to an input device having a structure in which an operation portion operated by an operator during an operation is retained stably.
2. Description of the Related Art
Conventionally, a position detection device is used generally in an electronics device or an electronics apparatus. The position detection device is mounted, for example, as a part of an input device of a computer, and is used for a device which determines a pointing position when an operator moves an operation element. In addition, the position detection device is mounted on a movable body such as a car, and is used for monitoring a position of the movable body.
The position detection device generally has a fixed part and a movable part moving relatively to the fixed part, and detects a change of position of the movable part by using a change of a light or a magnetic field (magnetic flux density). Japanese Patent Application Publication No. 2000-180114 (hereinafter referred to as Document 1) discloses, for example, a non-contact position detection device using a magnet. In the position detection device, two magnets are arranged at a fixed interval, and an electromagnetic conversion element is arranged between the two magnets. The magnets respectively arranged above and below form a diamond-shaped space in which a gap range at the middle thereof is larger than a range at the periphery thereof. The electromagnetic conversion element is arranged in the afore-mentioned space. The position detection device detects a position using a signal from the electromagnetic conversion element when either the magnet or the electromagnetic conversion element moves.
In addition, a pointing device is connected to a computer or the like, outputs the position information or the direction information, and is used in order to move a pointer or a cursor displayed on a display to a desirable position. The pointing device may be a more convenient one if the pointing device is capable of outputting a signal to select an icon displayed at the position together.
Japanese Utility Model Application Publication No. 7-49549 (hereinafter referred to as Document 2) discloses a pointing device having a structure in which an input button is arranged under a track ball. In addition, Japanese Patent Application Publication No. 2002-149337 (hereinafter referred to as Document 3) discloses a pointing device which has an operation portion moving on an X-Y plane. A switch is provided under the operation portion.
Further, another input device, which inputs an instruction using the position information of a movable object that an operator moves, has been known. The input device includes an operation portion which is moved by an operator's operation, and points a desirable position with the position of the operation portion. The input device is connected to a computer or the like. An operator moves the operation position and determines a pointing position on a display.
Document 3 discloses a pointing device to be connected to a computer. The pointing device has a position information input portion corresponding to the operation portion. When the pointing device slides, a pointer or a cursor displayed on a display, to which the pointing device is connected, moves in a corresponding direction.
In the position detection device disclosed in Document 1, however, at least one pair of magnets are arranged above and below facing each other, and the magnets form the diamond-shaped space. Therefore, there is a problem in that the production costs increase because of its complex structure around the electromagnetic conversion element. In addition, the position detection device has only one electromagnetic conversion element in the above-mentioned space. It is thus necessary to identify the position of the magnet on a two-dimensional plane by using an output signal from one electromagnetic conversion element. Accordingly, there are other problems that a signal processing is complicated and an accuracy of the position detection is reduced.
In addition, the thickness of the pointing device described in Document 2 is increased, because a portion that an operator operates has a ball shape. If the size of the ball is reduced in order to downsize the input device, the input device is difficult to operate. In the pointing device described in Document 3, the switch provided under the device is turned on when the operation portion is pressed. Hence, it is necessary to retain the operation portion on the switch in order to press down the switch. It is also necessary to move the operation portion in a region where the switch is provided. This switch mechanism may be provided in the operation portion. However, in this case, it is necessary to form a space to house the switch, interconnections, and so on in the operation portion. And, the structure is complicated and grows in size. This arises a problem that an operational feeling gets worse and the interconnection to the switch is easy to be cut off, because the interconnection is moved according to the movement of the operation portion.
Further, in the pointing device disclosed in Document 3, the range is narrow so that the position information input portion (the operation portion) can move. In such a narrow range, it is difficult to point an accurate position, because a pointer on the display moves rapidly, even if the operation portion moves just a little. It is thus preferable that the input device having the operation portion should be provided in a relatively large area so that the operation portion may move in the area. However, in this case, there is a problem that the operation portion moves unstably when it is not used, for example, when an instruction is not input or while the input device is being moved.